Local ordering in disordered NdxZr1-xO2-0.5x pyrochlore as observed using neutron total scattering

Devon Drey; Eric O'Quinn; Sarah Finkeldei; Joerg Neuefeind; Maik Lang

doi:10.1016/j.actamat.2021.117590

Local ordering in disordered Nd_xZr_1-_xO_2-0.5_x pyrochlore as observed using neutron total scattering

Devon Drey, Eric O'Quinn, Sarah Finkeldei, Joerg Neuefeind, Maik Lang

Research output: Contribution to journal › Article › peer-review

9 Scopus citations

Abstract

Pyrochlore complex oxides (A₂B₂O₇) are an important class of fluorite-derivative ceramics with exceptional chemical and structural versatility which make them ideal model systems for studying disordering mechanisms over a range of spatial scales. Neutron total scattering methods were used to analyze the structural behavior in the non-stoichiometric series Nd_xZr_1-_xO_2-0.5_x (0.5 ≤ x ≤ 0.23) as a function of Nd content, x. Characterization of the structure functions using Rietveld refinement and the pair distribution functions with small-box refinement reveal complex disordering pathways; the average, long-range phase changes over a very narrow compositional range from pyrochlore (Fd3¯m) to defect fluorite (Fm3¯m) through full randomization of the cation and anion sublattices at x ∼ 0.31, while the local, short-range structure continuously adopts a weberite-type atomic arrangement (C222₁). Comparison to a previously studied Ho₂Ti_2-_xZr_xO₇ solid solution series reveals how changes in chemical composition and stoichiometry modify defect formation and determine how disordering progresses across different length scales in pyrochlore oxides.

Original language	English
Article number	117590
Journal	Acta Materialia
Volume	225
DOIs	https://doi.org/10.1016/j.actamat.2021.117590
State	Published - Feb 15 2022
Externally published	Yes

Funding

This work was supported by the U.S. Department of Energy , Office of Science, Basic Energy Sciences, under Award DE-SC0020321. The research at ORNL's Spallation Neutron Source was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences, U.S. Department of Energy.

Keywords

Lanthanide-doped zirconia
Neutron diffraction
Order to disorder phase transformations
Pair correlation function
Short-range ordering

Access to Document

10.1016/j.actamat.2021.117590

Cite this

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title = "Local ordering in disordered NdxZr1-xO2-0.5x pyrochlore as observed using neutron total scattering",

abstract = "Pyrochlore complex oxides (A2B2O7) are an important class of fluorite-derivative ceramics with exceptional chemical and structural versatility which make them ideal model systems for studying disordering mechanisms over a range of spatial scales. Neutron total scattering methods were used to analyze the structural behavior in the non-stoichiometric series NdxZr1-xO2-0.5x (0.5 ≤ x ≤ 0.23) as a function of Nd content, x. Characterization of the structure functions using Rietveld refinement and the pair distribution functions with small-box refinement reveal complex disordering pathways; the average, long-range phase changes over a very narrow compositional range from pyrochlore (Fd3¯m) to defect fluorite (Fm3¯m) through full randomization of the cation and anion sublattices at x ∼ 0.31, while the local, short-range structure continuously adopts a weberite-type atomic arrangement (C2221). Comparison to a previously studied Ho2Ti2-xZrxO7 solid solution series reveals how changes in chemical composition and stoichiometry modify defect formation and determine how disordering progresses across different length scales in pyrochlore oxides.",

keywords = "Lanthanide-doped zirconia, Neutron diffraction, Order to disorder phase transformations, Pair correlation function, Short-range ordering",

author = "Devon Drey and Eric O'Quinn and Sarah Finkeldei and Joerg Neuefeind and Maik Lang",

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T1 - Local ordering in disordered NdxZr1-xO2-0.5x pyrochlore as observed using neutron total scattering

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AU - O'Quinn, Eric

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AU - Neuefeind, Joerg

AU - Lang, Maik

PY - 2022/2/15

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AB - Pyrochlore complex oxides (A2B2O7) are an important class of fluorite-derivative ceramics with exceptional chemical and structural versatility which make them ideal model systems for studying disordering mechanisms over a range of spatial scales. Neutron total scattering methods were used to analyze the structural behavior in the non-stoichiometric series NdxZr1-xO2-0.5x (0.5 ≤ x ≤ 0.23) as a function of Nd content, x. Characterization of the structure functions using Rietveld refinement and the pair distribution functions with small-box refinement reveal complex disordering pathways; the average, long-range phase changes over a very narrow compositional range from pyrochlore (Fd3¯m) to defect fluorite (Fm3¯m) through full randomization of the cation and anion sublattices at x ∼ 0.31, while the local, short-range structure continuously adopts a weberite-type atomic arrangement (C2221). Comparison to a previously studied Ho2Ti2-xZrxO7 solid solution series reveals how changes in chemical composition and stoichiometry modify defect formation and determine how disordering progresses across different length scales in pyrochlore oxides.

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